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FragmentStateAdapter removing last tab instead of current ViewPager2

ViewPager2 is removing last tab instead of current tab, same problem was occurring when i was using viewpager.
Also when selected tab is last one it removes last tab correctly
dependency
implementation "androidx.viewpager2:viewpager2:1.0.0"
This is main activity code
MainActivity.java
public class MainActivity extends AppCompatActivity {
TabLayout tabLayout;
ViewPager2 viewPager;
ViewPagerAdapter adapter;
Button btnAddTab,btnRemoveCurrentTab;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
viewPager = findViewById(R.id.view_pager);
tabLayout = findViewById(R.id.tabs);
btnAddTab=findViewById(R.id.btn_add);
btnRemoveCurrentTab=findViewById(R.id.btn_remove);
adapter=new ViewPagerAdapter(this);
viewPager.setAdapter(adapter);
new TabLayoutMediator(tabLayout, viewPager,
new TabLayoutMediator.TabConfigurationStrategy() {
#Override public void onConfigureTab(#NonNull TabLayout.Tab tab, int position) {
tab.setText("Store " + (position + 1));
}
}).attach();
btnRemoveCurrentTab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
adapter.removeFrag(tabLayout.getSelectedTabPosition());
}
});
btnAddTab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
DynamicFragment fView = new DynamicFragment();
adapter.addFrag(fView,"Store "+(adapter.getmFragmentIdList().contains(adapter.getItemCount()+1)?adapter.getItemCount()+2:adapter.getItemCount()+1),(adapter.getmFragmentIdList().contains(adapter.getItemCount()+1)?adapter.getItemCount()+2:adapter.getItemCount()+1));
}
});
}
}
ViewPagerAdapter
This is FragentStateAdapter
public class ViewPagerAdapter extends FragmentStateAdapter {
private final List<DynamicFragment> mFragmentList = new ArrayList<>();
private final List<Integer> mFragmentIdList = new ArrayList<>();
public ViewPagerAdapter(#NonNull FragmentActivity fragmentActivity) {
super(fragmentActivity);
}
#NonNull #Override public Fragment createFragment(int position) {
return DynamicFragment.newInstance(String.valueOf(position),mFragmentIdList.get(position));
}
public void addFrag(DynamicFragment fragment, String title, int id) {
mFragmentList.add(fragment);
Log.e("fragment id " ,""+id);
Log.e("fragment array " ,title+ mFragmentList.size());
mFragmentIdList.add(id);
notifyDataSetChanged();
}
public void removeFrag(int pos) {
Log.e("deleted frag",mFragmentIdList.get(pos)+" "+pos);
mFragmentList.remove(pos);
mFragmentIdList.remove(pos);
notifyDataSetChanged();
}
public List<Integer> getmFragmentIdList() {
return mFragmentIdList;
}
#Override
public long getItemId(int position) {
return super.getItemId(position);
}
#Override public int getItemCount() {
return mFragmentList.size();
}
}
Fragment
This is my dynamic fragment which i want to add and remove
public class DynamicFragment extends Fragment {
private static final String ARG_SECTION_NUMBER = "section_number";
private static final String ARG_ID = "id";
private String sectionNumber;
int id;
TextView textView;
EditText editText1,editText2;
public DynamicFragment() {
// Required empty public constructor
}
public static DynamicFragment newInstance(String sectionNumber, int id) {
DynamicFragment fragment = new DynamicFragment();
Bundle args = new Bundle();
args.putString(ARG_SECTION_NUMBER, sectionNumber);
args.putInt(ARG_ID, id);
fragment.setArguments(args);
Log.e("StoreDynamic","dynamic new instance");
return fragment;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootView= inflater.inflate(R.layout.fragment_dynamic, container, false);
textView=rootView.findViewById(R.id.textView);
editText1=rootView.findViewById(R.id.et1);
editText2=rootView.findViewById(R.id.et2);
sectionNumber = getArguments().getString(ARG_SECTION_NUMBER);
id=getArguments().getInt(ARG_ID);
editText1.setText(id+" "+sectionNumber);
textView.setText(id+" "+sectionNumber);
return rootView;
}
}

I ran into the same problem and the solution to this question: remove fragment in viewPager2 use FragmentStateAdapter, but still display worked for me. Mostly the part about overriding the getItemId function to return something other than the position to identify the item because the item's position changes when adding and removing fragments.

You need to overwrite the methods getItemId() and containsItemId()
as shown in this post: https://stackoverflow.com/a/57944197/870242
items variable holds your fragment (mFragmentList )
private val pageIds= items.map { it.hashCode().toLong() }
override fun getItemId(position: Int): Long {
return items[position].hashCode().toLong() // make sure notifyDataSetChanged() works
}
override fun containsItem(itemId: Long): Boolean {
return pageIds.contains(itemId)
}

Viewpager displaying the required details only once and not displaying it a second time when coming back from main screen

I am calling ViewPager(Fragment C) from a ListView(Fragment A). But this only works once. If I move back to my list and select another item , it doesnot move into the listview. It just shows a blank layout of fragment c.
Below is the code for Fragment A:
public class FragmentA extends Fragment implements AdapterView.OnItemClickListener{
ListView list;
Communicator communicator;
ArrayList<Book> book_a;
ArrayList<String> book_titles;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view= inflater.inflate(R.layout.fragment_a,container,false);
savedInstanceState = getArguments();
if (getArguments() != null) {
// savedInstanceState = getArguments();
book_a = (ArrayList<Book>) getArguments().getSerializable("bookarray");
book_titles = getList(book_a);
//Log.d("Frag_a:Title",book_a.get(5).getTitle());
list= (ListView) view.findViewById(R.id.listview);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(getActivity(),android.R.layout.simple_list_item_1,book_titles);
list.setAdapter(adapter);
list.setOnItemClickListener(this);
}
return view;
}
public ArrayList<String> getList(ArrayList<Book> book2){
ArrayList<String> list_titles = new ArrayList<String>();
int size = book2.size();
for(int i=0;i<size;i++){
Book object;
object = book2.get(i);
list_titles.add(object.title);
}
return list_titles;
}
public void setCommunicator(Communicator communicator)
{
this.communicator = communicator;
}
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
communicator.respond(position);
}
public interface Communicator{
public void respond(int index);
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
if(context instanceof Communicator){
communicator = (Communicator) context;
} else {
throw new RuntimeException(context.toString()+"must implement Communicator");
}
}
#Override
public void onDetach() {
super.onDetach();
communicator = null;
}
}
Below is the code for MainActivity:
public class MainActivity extends AppCompatActivity implements FragmentA.Communicator{
FragmentB f2;
ArrayList<Book> b = new ArrayList<Book>();
FragmentManager manager;
static int flag = 0;
static String search="great";
SearchView sv ;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
sv = (SearchView) findViewById(R.id.searchView);
sv.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
#Override
public boolean onQueryTextSubmit(String query) {
flag = 1;
search = query;
getBooks();
return false;
}
#Override
public boolean onQueryTextChange(String newText) {
getBooks();
return false;
}
});
getBooks();
/*
manager = getSupportFragmentManager();
f1 = (FragmentA) manager.findFragmentById(R.id.fragment);
f1.setCommunicator(this);*/
}
#Override
public void respond(int index) {
f2 = (FragmentB) manager.findFragmentById(R.id.fragment2);
if(f2!=null && f2.isVisible())
{
f2.changeData(index);
}
else
{
Bundle bundle = new Bundle();
bundle.putInt("index", index);
bundle.putSerializable("bookarray",(ArrayList<Book>)b);
Fragment newFragment = new FragmentC();
newFragment.setArguments(bundle);
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragment, newFragment);
transaction.addToBackStack(null);
transaction.commit();
}
}
public void afterGetBooks(ArrayList<Book> bks) {
for (Book h : bks) {
b.add(h);
}
manager = getSupportFragmentManager();
Bundle args = new Bundle();
args.putSerializable("bookarray",(ArrayList<Book>)bks);
FragmentA f1 = new FragmentA();
f1.setArguments(args);
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.fragment,f1);
transaction.addToBackStack(null);
transaction.commit();
f1.setCommunicator(this);
}
private void getBooks(){
String url;
if(flag==0){
url = "https://kamorris.com/lab/audlib/booksearch.php/";}
else{
url = "https://kamorris.com/lab/audlib/booksearch.php?search=" + search;
flag=0;
}
//ArrayList<Book> boo;
Retrofit retrofit = new Retrofit.Builder().baseUrl("https://kamorris.com/lab/audlib/booksearch.php/").addConverterFactory(GsonConverterFactory.create()).build();
Book.API api = retrofit.create(Book.API.class);
Call<ArrayList<Book>> call = api.getBooks(url);
call.enqueue(new Callback<ArrayList<Book>>() {
#Override
public void onResponse(Call<ArrayList<Book>> call, Response<ArrayList<Book>> response) {
ArrayList<Book> Books = response.body();
for(Book h: Books){
Log.d("Retro-Title",h.getTitle());
//b.add(h);
}
afterGetBooks(Books);
}
#Override
public void onFailure(Call<ArrayList<Book>> call, Throwable t) {
Toast.makeText(getApplicationContext(),t.getMessage(),Toast.LENGTH_SHORT).show();
}
});
}
Below is the code for Fragment C:
public class FragmentC extends Fragment {
ViewPager vp;
static int list_pos;
FragmentPagerAdapter adapterViewPager;
public static ArrayList<Book> book_c;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_c,container,false);
if(getArguments()!= null){
book_c = (ArrayList<Book>) getArguments().getSerializable("bookarray");
list_pos = getArguments().getInt("index");
}
vp = (ViewPager) view.findViewById(R.id.viewpager);
adapterViewPager = new MyPagerAdapter(getFragmentManager());
vp.setAdapter(adapterViewPager);
return view;
}
public static class MyPagerAdapter extends FragmentPagerAdapter {
private static int NUM_ITEMS = 11;
public MyPagerAdapter(FragmentManager fragmentManager) {
super(fragmentManager);
}
// Returns total number of pages
#Override
public int getCount() {
return NUM_ITEMS;
}
// Returns the fragment to display for that page
#Override
public Fragment getItem(int position) {
switch (list_pos) {
case 0: // Fragment # 0 - This will show FirstFragment
list_pos = position;
return FragmentB.newInstance(book_c,0);
case 1: // Fragment # 0 - This will show FirstFragment different title
list_pos = position;
return FragmentB.newInstance(book_c,1);
case 2: // Fragment # 1 - This will show SecondFragment
list_pos = position;
return FragmentB.newInstance(book_c,2);
case 3: list_pos = position;
return FragmentB.newInstance(book_c,3);
case 4:list_pos = position;
return FragmentB.newInstance(book_c,4);
case 5:list_pos = position;
return FragmentB.newInstance(book_c,5);
case 6:list_pos = position;
return FragmentB.newInstance(book_c,6);
case 7:list_pos = position;
return FragmentB.newInstance(book_c,7);
case 8:list_pos = position;
return FragmentB.newInstance(book_c,8);
case 9:list_pos = position;
return FragmentB.newInstance(book_c,9);
default:
return null;
}
}
// Returns the page title for the top indicator
#Override
public CharSequence getPageTitle(int position) {
return "Page " + position;
}
}
}
Also is there a way, where I can start my viewpager from the description of the listitem which I selected.
Also Fragment B is just a text view holder.
I tried to see the control flow with the debugger. But when I try it that way these lines in Fragment C are not working ..
{
book_c = (ArrayList<Book>) getArguments().getSerializable("bookarray");
list_pos = getArguments().getInt("index");
}
vp = (ViewPager) view.findViewById(R.id.viewpager);
adapterViewPager = new MyPagerAdapter(getFragmentManager());
vp.setAdapter(adapterViewPager);

Your fragment has not been destroyed and therefore when it is brought back, onCreateView is not being called. Instead override setUserVisibleHint.
#Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (isVisibleToUser) {
// This is true when your fragment is visible, write code to populate view here
} else {
// This is true when your fragment is hidden.
}
}

The solution i found is to change the Fragment Manager
adapterViewPager = new MyPagerAdapter(getFragmentManager());
to
adapterViewPager = new MyPagerAdapter(getChildFragmentManager());

ViewPage - Change the icon on the text

I faced with a problem I can not solve. How can you replace icons in the text resource. Let's say instead of the first icons - current , the second icon - finished .
public class ViewPageAdapter extends FragmentPagerAdapter implements PagerSlidingTabStrip.CustomTabProvider {
private Context mContext;
private final int[] ICONS = {
R.drawable.selector_icon_active,
R.drawable.selector_icon_inactive
};
public ViewPageAdapter(FragmentManager fm, Context context) {
super(fm);
mContext = context;
}
#Override
public void tabUnselected(View view) {
view.setSelected(false);
}
#Override
public void tabSelected(View view) {
view.setSelected(true);
}
#Override
public View getCustomTabView(ViewGroup parent, int position) {
FrameLayout customLayout = (FrameLayout) LayoutInflater.from(mContext).inflate(R.layout.custom_tab, parent, false);
((ImageView) customLayout.findViewById(R.id.image)).setImageResource(ICONS[position]);
return customLayout;
}
#Override
public CharSequence getPageTitle(int position) {
// return null;
return super.getPageTitle(position);
}
#Override
public int getCount() {
return ICONS.length;
}
#Override
public Fragment getItem(int position) {
Bundle bundle = new Bundle();
switch (position) {
case 0:
default:
bundle.putSerializable("TYPE", NotificationsType.ACTIVE);
break;
case 1:
bundle.putSerializable("TYPE", NotificationsType.INACTIVE);
break;
}
Fragment fragment = new TabFragment();
fragment.setArguments(bundle);
return fragment;
}
}

ViewPager get fragment reference

I have activity where I have created a viewpager that contains two fragments. I need to get a reference to the existing fragment or it's view, in the activity to refresh the list from the fragment if necessary. I was looking for a solution for two days, but found nothing on this occasion.
So here is my adapter
public class SearchPagerAdapter extends FragmentStatePagerAdapter {
CharSequence Titles[];
int NumbOfTabs;
public SearchPagerAdapter(FragmentManager fm,CharSequence mTitles[], int mNumbOfTabsumb) {
super(fm);
this.Titles = mTitles;
this.NumbOfTabs = mNumbOfTabsumb;
}
#Override
public Fragment getItem(int position) {
if(position == 0)
{
FragmentAyahSearch tab1 = new FragmentAyahSearch();
return tab1;
}
else
{
FragmentSurahList tab2 = new FragmentSurahList();
return tab2;
}
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
super.destroyItem(container, position, object);
}
#Override
public CharSequence getPageTitle(int position) {
return Titles[position];
}
#Override
public int getCount() {
return NumbOfTabs;
}
}
below, I create a viewpager and adapter in MainActivity
searchAdapter = new SearchPagerAdapter(getSupportFragmentManager(), searchTitles, Numboftabs);
pager.setAdapter(searchAdapter);
tabs.setViewPager(pager);
I hope you will help me, because I'm losing my mind over this.

I would suggest maintain a list like
private List<Fragment> frag = new ArrayList<Fragment>();
then
public class SearchPagerAdapter extends FragmentStatePagerAdapter {
CharSequence Titles[];
int NumbOfTabs;
public SearchPagerAdapter(FragmentManager fm,CharSequence mTitles[], int mNumbOfTabsumb) {
super(fm);
this.Titles = mTitles;
this.NumbOfTabs = mNumbOfTabsumb;
}
#Override
public Fragment getItem(int position)
{
Fragment fragment = frag.get(position);
if(fragment == null )
{
if (position == 0)
{
fragment = new FragmentAyahSearch();
}
else
{
fragment = new FragmentSurahList();
}
}
return fragment;
}
#Override
public CharSequence getPageTitle(int position) {
return Titles[position];
}
#Override
public int getCount() {
return frag.size();
}
now if you want the reference of any fragment
just call , frag.get(<position>) will return you desire frgament

how to jump to Fragment upon selection of respective tab bar

//SampleTabsWithIcons.java
public class SampleTabsWithIcons extends FragmentActivity {
private static final int[] ICONS = new int[] {
R.drawable.events,
R.drawable.rss,
R.drawable.user,
R.drawable.bell,
R.drawable.search
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.simple_tabs);
FragmentPagerAdapter adapter = new GoogleMusicAdapter(getSupportFragmentManager());
ViewPager pager = (ViewPager)findViewById(R.id.pager);
pager.setAdapter(adapter);
TabPageIndicator indicator = (TabPageIndicator)findViewById(R.id.indicator);
indicator.setViewPager(pager);
}
class GoogleMusicAdapter extends FragmentPagerAdapter implements IconPagerAdapter {
public GoogleMusicAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
return TestFragment.newInstance(ICONS[position % ICONS.length]);
}
#Override public int getIconResId(int index) {
return ICONS[index];
}
#Override
public int getCount() {
return ICONS.length;
}
}
}
//TestFragment.java
public final class TestFragment extends Fragment {
private static final String KEY_CONTENT = "TestFragment:Content";
public static TestFragment newInstance(int icons) {
TestFragment fragment = new TestFragment();
StringBuilder builder = new StringBuilder();
for (int i = 0; i < 20; i++) {
builder.append(icons).append(" ");
}
builder.deleteCharAt(builder.length() - 1);
fragment.mContent = builder.toString();
return fragment;
}
private String mContent = "???";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if ((savedInstanceState != null) && savedInstanceState.containsKey(KEY_CONTENT)) {
mContent = savedInstanceState.getString(KEY_CONTENT);
}
}
#SuppressWarnings("deprecation")
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
TextView text = new TextView(getActivity());
text.setGravity(Gravity.CENTER);
text.setText(mContent);
text.setTextSize(20 * getResources().getDisplayMetrics().density);
text.setPadding(20, 20, 20, 20);
LinearLayout layout = new LinearLayout(getActivity());
layout.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
layout.setGravity(Gravity.CENTER);
layout.addView(text);
return layout;
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putString(KEY_CONTENT, mContent);
}
}
//TestFragmentAdapter.java
class TestFragmentAdapter extends FragmentPagerAdapter implements IconPagerAdapter {
private static final int[] ICONS = new int[] {
R.drawable.events,
R.drawable.rss,
R.drawable.user,
R.drawable.bell,
R.drawable.search
};
private int mCount = ICONS.length;
public TestFragmentAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
return TestFragment.newInstance(ICONS[position % ICONS.length]);
}
#Override
public int getCount() {
return mCount;
}
#Override
public int getIconResId(int index) {
return ICONS[index % ICONS.length];
}
public void setCount(int count) {
if (count > 0 && count <= 10) {
mCount = count;
notifyDataSetChanged();
}
}
}
and my output is,
My question is instead of displaying numbers while selecting each tabs, I want to go to new fragment activity (ie, newpage.java). Now some numbers are showing on each tab selection. How can i implement this.
I have 5 class (first.java,second.java,third.java,four.java,five.java) and 5 layout for each tabs (first.xml... respectively)
I tried a lot but no success. Does anyone know the answer.
Thanks.

Ok you can make your own Fragments and then return them in the getItem(int position); for example, you could have an array of your Fragments calendar, feed, etc. then on each position you return one.
//SampleTabsWithIcons.java
Fragment[] tabFragments = new Fragment[] {CalendarFragment.newInstance(),
FeedFragment.newInstance()}
.....
#Override
public Fragment getItem(int position) {
return tabFragments[position];
}

You can simply use this and set the tab to the viewPager ...
#Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
viewPager.setCurrentItem(tab.getPosition());
}

Inside fragment pager adapter you can do like this.
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
frag = UsageRecoSummaryFragemrent.newInstance(position);
// changeColor(newColor);
break;
Inside fragment
public static UsageRecoSummaryFragemrent newInstance(int position) {
UsageRecoSummaryFragemrent f = new UsageRecoSummaryFragemrent();
Bundle b = new Bundle();
b.putInt(ARG_POSITION, 0);
f.setArguments(b);
return f;
}